Zircon refractory



Patented Aug. 23, 1932 UNITED STATES WILLIAM G. isaonxsrnn'r, or JAMAICA, NEW YORK, Assr'crnort rononERrYnnsnARcH COMPANY, OF NEW YORK, N. Y.,

A oo rort' TroN on DELAWARE ZIRCON REFRACTORY :1

No Drawing. Application filed November 11, 1926,, Seria1 No. l4 7,8f47;-"ltenewed May 20, 1930.

This invention relates'to the manufacture of zircon refractories and is based primarily on my discovery that phosphoric acid may be used as a bonding agent for zircon partiamounts as small as one-tenth per cent by weight of the finished product calculating the 10 phosphoric acid in terms of phosphorus pentoxide P In general however I have found it to be more practical to employ a greater proportion of phosphoric acid than that indicated as being merely sufficient to y p M h p it, however, to be wlth n the scope of my 111- efi'ect coherence of the zircon particles. The most desirable minimum of P 0 is about three per cent. Much greater proportions of I v I y l p ofa phosphate which'does 'not decompose at a 'low temperature, to treat the phosphate with nan acid capable; of; decomposing the phosthe acid may be used but due to its hygroscopic nature it willusually not be. practical to employ a greater proportion than thirteen per cent calculated, in terms of P 0 In addition to discovering that phosphoric acid is a suitable bonding agent for zircon.,. I have further discovered that by varying the amount of the acid in the mixture (zircon phosphoric acid mixture) ,1 am enabled to control the change in volume of the mixture during firing incident to bonding. Thus I d have found that if the P 0 forms approxito-prevent its ultimatedeterioration by mo1s-v mately six per cent by weight of the mixture the latter will neither expand nor contract On.-

during firing to bonding temperature. the other hand if the P 0 content is only three per cent, the mixture on firing will shrink about two and one-fourths per cent While if it contains nine per cent of P 0 it will expand about six-tenths per cent. It will therefore be seen that a material increase of P 0 over six per cent causes some expansion of the mixture during firing while a material decrease below six per cent causes a material shrinkage of the mixture during firing. The property of the zircon phosphoric acid mixture to maintain its prefiring volume substantially constant during firing or to shrink or expand in conformity with the percentages above specified depends in a measure on the fines present in the aggregate. The figures above given are based on a zircon aggregate consisting of approximately equal. parts of partially dehydrated. f The higher-the firing natural grain particles and milled. grain of QOQ-meshor finen. Theinvention in its'broad aspect is however not limited to any particular proportionbetween natural grain and Iprefer to nix the [zircon particles with phosphoric acid ass'uc'h, more particularly orthophosphoric' acid, not only on account of --its relativecheapness' but primarily because "1 thereby avoid the introduction10f undesirable substances into the mixtureythat is to say, substances which would be va factor in determining the-desirability orsuitability of flpr d t fo pa i lar 3 I c n de vention to ,mix' the" zircon; with ,a phosphate, either organic or 1norgan c,]and 1n the case ph ate.

i one of theiniportaiit features of the present invent'ion'is that; akfirmly 'jcoherent prod- 'u'ct of subst'antiallymaximum strength is P o uc d Wh nt ilj i' lilf Ii' d o. a, P' r i .;"t e. e gh erhood of .420 F. However-if therefractory is to be exposedto "a moist'atmosphere it necessary that it be firedto a much higher temperaturelin order ture. Absorption of moisture by the prod- ,uct fired to only 420,F. Icons'ider to bejdue to the fact that. the. phosphoric acidisonly temperature the fmore stable becomes the refractory product because of more complete dehydration'of the acid. 'When fired to temperatures in the neighborhood of 1800 F. to 2000 F., the resultant product shows no tendency to deteriorateon prolonged expo-.. sure to moisture. As a general rule, however, firing temperatures of approximately 750 F. will be found amply suflicient to give a product, having sufiicient stability for most purposes especially where the P 0 content is not substantially in excess of six percent. The refractory produced according to my invention is highly resistant to heat, is hard finds many specialapplications in the arts. As an instance of such application may be mentioned its suitability as a cylinder lining for internal combustion engines. It is also V 5 admirably adapted for use as molds for metal die casting. I Y p What I claim is: 1. A method of bonding zircon particles to form a refractory body whose Volume after i a m bonding is substantially the same as its vol- I ume before bonding comprising heating said particles admixed with such an amount of phosphoric acid that the acid calculated as phosphorus pentoxide equals approximately six percent of the dry product. 7 L

' 2. A method of bonding zircon particles to form a refractory body whose volume after bonding is substantially the same'as its'volume'before bondingcomprising heating said 3 particles admixed with such an'amount'of fphosphoricacid that the acid calculated'as phosphorus pentoxide equals approximately six percent'of the dry product, the Zircon particles being *an aggregate of fines and aynatural; grains. v V

H 3. method of bonding zircon particles 'to form a refractory body whose volume after bonding is substantially the same as its Volume before bonding comprising heating 30 said particles admixed with such an amount 7 of phosphoric acid that the acid calculated. as phosphorus pentoxide equals approximate- 1y six'per cent of the dry productythezircon" particles being an aggregate of approximate- ":15' 1y equal parts of natural grains and milled grainofrelatively, fine size. T I i 4', A'method of bonding zircon particles o to form a refractory body whose Volume after bonding is substantially the same as its vol- 4o 'b f i e bonding comprising heating'said particles admixed with 'such an amount of I phosphoric acid that the acid calculated as phosphorus pentoxide equals approximately six percent of the dry product, the heating temperature being between 550 and 750 F.

V 5. A refractory product consisting of zircon bonded by the reaction products of phosphoric acid, the acid calculated as P 0 constituting six percent of the product. a

In testimony whereof I'afiix my signature.

' WILLIAM G. BJOR K STED'IY 

